All posts tagged glacier melt

It’s well known now that massive glaciers in Greenland and Antarctica are contributing to an accelerating global sea level rise. And while we first thought Greenland was primarily at risk of producing ocean-lifting melt this Century, we have now learned that both West and East Antarctica are becoming involved.

(A massive glacier the size of France is floating on more of a warming ocean than previously thought. Taking into account past reports of thinning along the glacier’s underside, and this is a rather concerning finding. Image source: Australian Antarctic Division.)

How much and how soon and under how much warming pressure is still a matter of some debate in the sciences. But the situation is now looking a bit worse for the Totten Glacier — an enormous sea-fronting slab of ice as big as France that if it melted in total would, by itself, raise sea levels by about 10-13 feet globally.

After follow-on expeditions to Totten, scientists (over the past two years) discovered that the glacier’s floating underside was losing about 10 meters of thickness annually even as its seaward motion was speeding up. Now, new research has found that more of the Totten Glacier is floating upon this warming flood of ocean water than previously thought. According to Professor Paul Winberry, from Central Washington University, who spent the austral summer of 2018 with a Tasmania-funded team of scientists taking measurements of Totten:

“A hammer-generated seismic wave was used to ‘see’ through a couple of kilometres of ice. In some locations we thought were grounded, we detected the ocean below indicating that the glacier is in fact floating (emphasis added).”

(Warm water invasion pathways have opened along Totten’s previous grounding line. These openings have allowed water to flood far inland beneath the glacier. The result is a less stable, more rapidly moving ice sheet. Image source: Jamin Greenbaum/University of Texas-Austin.)

This warm water breakthrough has contributed to Totten’s seaward movement. And the new study was aimed at discovering the extent of the inland water melt flood. According to lead researcher Dr Galton-Fenzi:

“These precise measurements of Totten Glacier are vital to monitoring changes and understanding them in the context of natural variations and the research is an important step in assessing the potential impact on sea-level under various future scenarios.”

The fact that the extent of inland flooding along Totten’s underside runs further than previously thought is a concern in light of recent findings that the glacier is losing a considerable amount of underbelly ice each year. In addition, the fact that we haven’t yet pinpointed the grounding line should add another note of worry. How much we should worry is unclear at this time. But the fact is that the scientific signs coming in from Totten continue to indicate that the glacier is suffering warming impacts that pose risks to its historic stability.

Svalbard. Until lately, a little-known locale situated between the previously frigid extreme North Atlantic and the Arctic Ocean about 500 miles east of Greenland. Typically a frozen island Archipelago, this pristine and sparsely inhabited redoubt has, over the past few years been ground zero for the assaults of an ongoing and extreme polar heat amplification.

During winters, temperatures in Svalbard are generally, well, Arctic. But in recent years abnormal winter warmth featuring temperatures ten, twenty, even thirty degrees above 20th century averages have been experienced with increasing frequency. This year, during one of the warmest winters on record for the Arctic, local Svalbard temperatures rocketed to as much as 40 degrees F above the usual range and for extended periods remained in the range of +20 to +30 F positive anomaly.

For all of February of 2014, the average temperature for this Arctic island chain was -1 C (about 30 F), a full 15 degrees C above average and a period that featured many readings at or above freezing. It was an unprecedented event for an island that features one of the largest ice caps on Earth.

Austfonna, Svalbard’s Ice Giant, Takes a Fall

Austfonna sprawls across the northeast section of Nordaustlandet, one of Svalbard’s many islands. The ice cap covers fully 8,000 square miles and features an ice dome pinnacle looming 750 meters high making it the largest of its ilk. Though not as grand as the great ice sheets of Greenland or West Antarctica, Austfonna still contains an immense amount of water. Less stable than ice sheets, deteriorating ice caps currently contribute to almost 50% of global sea level rise.

But Austfonna, the largest of these, was thought to be somewhat insulated from the insults plaguing most of the world’s ice caps. Its far northern and previously frigid location at Svalbard made it less vulnerable. But that was before sea ice loss opened the gates to an ongoing and ever-increasing assault of warm winds.

Now, according to findings made by the European Space Agency’s (ESA) Sentinel 1 Spacecraft, it appears that the ongoing assault of heat has at last destabilized the great Austfonna. For according to radar altimetry readings, the pace of the ice cap’s motion toward the Barents Sea has, over the past three years, accelerated to an extraordinary speed ten times more rapid than its previous pace (Sentinel’s findings are due to be published soon in a prominent scientific journal).

Lead study author Prof Andy Sheperd of Leeds University notes:

“We’ve observed Austfonna with various satellite radar datasets over the past 20 years, and it hasn’t done very much. But we’ve now looked at it again with the new Sentienl-1a spacecraft, and it’s clear it has speeded up quite considerably in the last two or three years. It is now flowing at least 10 times faster than previously measured.”

Austfonna is just the most recent of many very large ice caps, ice sheets, or glaciers now showing increasing rates of motion toward the world ocean. In many cases, once destabilized, these great bodies of frozen water have reached a point of no return as they lunge toward an inevitable destiny of melt, outflow, and disintegration. The most recent and ongoing rash of destabilizations are likely to have significant implications for global sea level rise due to human caused warming going forward. And with human heat forcing and amplifying Earth System feedbacks still on the rise, the glacial butcher tally isn’t likely to end any time soon.

Polar amplification. It’s kind of a dirty word in the climate science community. It’s, what would seem, a counter-intuitive displacement of much of the warming world’s heat over some of its coldest regions, during its coldest seasons.

It’s not the curse word that everyone can’t say. No, that’s more likely hydrogen sulfide gas — the veritable F-word of the oceanic climate community and only slightly worse than the M-word, methane. But it’s an uncomfortable term nonetheless because it brings up some rather uncomfortable issues.

Like why, for example, would the Arctic suck up so much of the world’s extra greenhouse gas accumulated heat during winter? And at what point, after taking on so much of this heat, do the seasons begin to change? At what point does winter, for the North, begin its slow and tumultuous, decades-to-centuries long, death? Are we now starting to see the strange attractors? Those excession offspring in the climate models. Emergent properties of Earth systems parameters wrenched into horrible forms by amplifying feedbacks?

(Temperatures above 80 North have remained above average since January 1. Temperatures in the same zone for the past ten days have averaged 13 C above the, already warmer than average, 1954 to 2014 mean. These temperatures are roughly equal to those typically seen in May. Other regions of the Arctic, as discussed below, have also shown extraordinary warmth. Image source: DMI.)

If there are people to look back at this time, hundreds of years from now, people who still retain the knowledge and tools today afforded to us by science and a clear, unadulterated recollection of this era of history, they would point to these years and say that this period was when the first evidence of winter’s eminent demise in the north became visible.

For winter is indeed dying, the victim of our ongoing and increasing emission of heat trapping gasses. And it would take a miraculous reversal and intervention, at this point, to save her.

This massive polar amplification, the consequence of the hottest Arctic conditions in at least 44,000 years, induced amazing sea ice losses since 1979, tripping the polar region and related weather patterns into new, far less stable, states. Such sea ice losses have been implicated in various far-reaching effects from a drying and baking of the American West to vicious alterations in the polar Jet Stream resulting in 11 month long blocking patterns and weather conditions that tend to remain stuck over regions for months and months on end.

And all this was happening during winter time. During the time when these furthest north locales were supposed to be coldest, certainly colder than down south, which, in many instances, was not the case.

200,000 square kilometers of sea ice lost in early February

But the above isn’t all in the long list of heat-caused extremes for the Arctic during the winter of 2013-2014. Now we can add to that tally a significant sea ice melt in the midst of winter.

As heat built in the Arctic over the most recent extreme warming episode, it tended to focus on two regions along the sea ice edge now vulnerable to episodes of winter-time melt. First, in the Bering Sea, where warmth has been almost continually flooding up along the high pulse of an 11 month blocking pattern and then in Baffin Bay, where warmer than normal winds have drawn heat up along coastal areas adjacent to the western slopes of Greenland creating anomalous conditions there.

For the Bering Sea, conditions were particularly grim. Throughout the season, sea ice measures have remained about half their normal values and by the end of January had settled about 100,000 square kilometers lower than during a normal season, leaving the ice state for this, typically frozen, sea a mere shade of past winter ice states. But in early February, with the flush of new warmth coming up from the south, ice totals fell by another 100,000 square kilometers at a time when the ice should have been expanding, leaving the Bering Sea about 250,000 square kilometers below average.

As mentioned above, Baffin Bay went through a similar, if less extreme, melt in early February falling from about 1 million square kilometers of sea ice to about 900,000 square kilometers from January 30 to February 2 before showing a slight uptick over the past day. Overall, Bering Sea ice area is its lowest on record for this time of year while Baffin Bay is currently seeing its third lowest year in the record.

Now, with melt season less than a month away, it is still possible that the Bering Sea and Baffin Bay may yet see some added freeze through March. But the weather pattern, at least over the next seven days, is not favorable for such an event and long range models seem to indicate continued flows of warmer than normal air to both of these vulnerable regions.

Greenland shows sporadic melt during Winter

In addition to the fits of sea ice melt occurring during coldest months in nearby Baffin Bay, the West Coast of Greenland is also showing patchy melt during the period. Model and sensor measures of the Greenland ice sheet provided by DMI showed patchy melt and ice mass loss not only in the most recent assessment, but also throughout the month of January.

(Ice Mass Balance for Greenland on February 3 on the left, 2014 compared to the, already warm, 1990-2011 base period on the right. Note the small but visible areas of pink indicating patches of ice mass loss along Greenland’s Western and Southeastern Coastal zones in the 2014 map. Also note the notably larger areas of ice mass gain in the 1991-2008 base period map which shows almost no areas of ice loss. Image source: DMI)

Certainly, these are small melt zones, but any Greenland melt during February is worth sitting up and taking notice of.

As Greenland struggled not to melt during what should be the frigid month of February, a scientific report released this week in the journal The Cryosphere provided yet more evidence of its ongoing thaw and glacial destabilization. The report, also covered in LiveScience, showed the Jakobshavn Isbrae glacier had more than tripled its 1990s speed as of 2013.

According to reports, the glacier had sped up to 150 feet per day (11 miles per year) during the summer of 2012 and had maintained this forward velocity through the summer of 2013. The glacier slowed somewhat during winter, but only to about 8.6 miles per year, resulting in a combined average speed of about 10 miles per year. By contrast, the glacier’s rush to the sea during the 1990s was considerably slower, at less than 3 miles per year and, by 2000, the glacier had sped up to around 6 miles per year, about half the current rate.

Overall, this single glacier has contributed about 1 millimeter to sea level rise over the past decade. It is worth noting that Greenland hosts hundreds of sea terminating glaciers, 99% of which are speeding up or increasing their melt rates.

“We’ve been watching it for over a decade now, so it was quite a surprise when it popped up in 2012 with these unusually high speeds,” said Ian Joughin, lead study author and a glaciologist at the University of Washington’s Polar Science Center in Seattle.

Unfortunately, glaciologists expect the Jakobshavn Isbrae glacier to speed up by a factor of 10 during the coming decades, dumping more than 35 miles worth of glacial ice into the ocean each year.